Jethalal S. Zaveri
Prof. Muni Mahendra Kumar
The most spectacular proof of relevance of relativity theory in particle physics was the creation of material particles from pure energy. Up till now, the basic question was whether the matter can be divided again and again until one arrived at the smallest indivisible unit. In relativistic particle physics, the only way to further divide subatomic particles is to bang them together. When they collide with high energies, they do break up but the pieces are not smaller than the original particles, but particles of the same kind. We can never obtain smaller pieces because new particles are constantly created out of the energy involved in the process of breaking up. The subatomic particles are thus divisible but at the same time indestructible. Such a paradox is inevitable with the static view of matter composed of basic building blocks. But it disappears when particles are viewed as 'processes', which involve energy appearing as their mass. Because of the high-energy collision process, 'particle physics' is also called 'high-energy physics'.
Most of the particles created by collisions have an extremely short life - less than a millionth of a second, after which they disintegrate into one of the three stable particles, viz., protons neutrons, and electrons. In spite of this, they can be detected, photographed and their properties can be measured. They can be produced in the laboratory in the so-called bubble chambers. The high energy-scattering experiments of the last few decades have firmly established that matter is completely mutable.
All particles can be transmuted into other particles; they can be created from energy and can vanish into energy. In this subatomic universe, classical concepts such as "elementary particles", "basic building blocks", "material stuff" or "isolated object" become meaningless. "A dynamic web of inseparable energy patterns" is a fit description of this world. This means that the properties of a particle can be known only in terms of its interaction with surrounding environment, and therefore, the particle has to be understood as an integrated part of the whole and never as an isolated entity. All particles contradict each other in many ways but all of them reflect the basic unity and intrinsically dynamic character of matter.
Relativity theory has not only affected our conception of particles but also our picture of the forces between these particles. Relativistic the forces between the particles are also other particles. This four-dimensional space-time character of the subatomic world is very difficult to visualize nor can our language deal with this concept adequately. And yet it is essential for understanding the subatomic properties where force and matter, which had seemed two entities, are unified. Subatomic particles are both matter and force, and this fact is a reason why they can be never subdivided into elementary components. As we shall see later, even protons and neutrons are not elementary but composite objects; but the classical distinction between the force and matter vanishes when the forces are also particles and cannot be decomposed into components.
But old ways die-hard and there are physicists who continue the old way of thinking and continue their search for the elementary building blocks of the material universe. The most likely candidate for this title is the 'quark'. It is a type of hypothetical particle theorized by Murray Gell Mann in 1964.
